Mechanical properties and modelling of superior high-performance steel at elevated temperatures

Abstract

Steel structures have been increasingly applied in contemporary infrastructures, which always require high loading capacities and strong resistance to disasters such as earthquake actions, fire and environmental corrosion, etc. Recently a superior high-performance (SHP) steel is developed accordingly, possessing combined beneficial features of high-strength, high-ductility, corrosion-resistance and fire-resistance, which may well satisfy the structural requirements. The present study aims to investigate mechanical properties of the SHP steel at elevated temperatures and to propose its constitutive models for further usage in fire design and analyses of structural members. A comprehensive experimental programme including a series of standard tensile coupon tests at both ambient and elevated temperatures is described herein, and key mechanical properties including modulus of elasticity, yield strength, ultimate tensile stress as well as stress-strain curves of the SHP steels are obtained based on the test results. Reduction effects of elevated temperatures on their mechanical properties are quantitatively clarified, and further comparisons with prediction results in accordance with national standards as well as with independent test results reported in literature are made. It is indicated that the mechanical properties of the SHP steels differ significantly from that of conventional mild steel and fire-resistant steel. Specific prediction equations are proposed for evaluating the temperature-dependent mechanical properties of the SHP steel; furthermore, an adapted Ramberg-Osgood model is developed for describing its full range stress-strain relation. The research outcomes of the present research may serve as an essential basis for better understanding mechanical performance of the SHP steel at elevated temperatures as well as for further investigations on its structural members' behaviour; and it is helpful to promote its application in practice.